Passivhaus Affiliate

Passivhaus in the foothills of Caerphilly

ising up the slope of Caerphilly Mountain, on the site of the old magistrate's court, a new development of Passivhaus homes for social housing is currently taking shape. The main block provides 34 apartments for the over 55s, a mix of 1- and 2-beds. A small stepped terrace of four 3 bedroom houses for general needs will complete the scheme’s provision of high quality, warm and comfortable Passivhaus homes for local people.

Caerphilly Magistrates Court development - terrace | Linc Cymru

Caerphilly Magistrates Court development | Linc Cymru

Key facts

Start date:

Completion date:

Number of units:



September 2018

April 2020

34 flats
4 houses

Direct electric (flats)
ASHP (houses)

1896m² (flats)
350m² (houses)


Innovation and tradition

The project has been part funded by a grant from the Welsh Government through their Innovative Housing Programme (IHP): on completion, this will be the largest Passivhaus development so far in Wales, and as such will lead the way in demonstrating how to scale up Passivhaus for the masses.

Caerphilly Magistrates Court development | Linc Cymru


On this project, innovation and an eye on the future is being balanced with tradition. The local contractors’ learning curve has been limited to those elements where the Passivhaus standard requires a step change in techniques and approach: excellent levels of airtightness, attention to detail, and consistency with details as designed. The basic construction, however, relies on traditional build methods that the contractors are already familiar and comfortable with: brick and block with a parge coat and full fill mineral wool cavity insulation.


Predicted energy performance



Thermal Energy demand (≤15kWh/m2.yr):



Thermal Energy load (≤10W/m2):



Primary Energy Renewable Demand (PER):



Primary Energy Renewable Generation (PER):    




Rising quality, falling costs

Key team





 Structural Engineer: 


Linc Cymru
Housing Association

Childs & Sulzmann

Hoare Lea

Jehu Project Services

Smarts Associates


The team at Linc Cymru anticipates that as Part L is revised, and the baseline requirements for levels of insulation, airtightness and indoor air quality start to rise - in turn necessitating the inclusion of MVHR as well as higher quality delivery across a project - the cost differential between a Passivhaus and a building regs project will shrink.

From a contractor’s point of view, having Passivhaus experience will also give them a competitive advantage for all projects, even when building to regs. Those skills and techniques learned in order to meet the Passivhaus standard don’t get forgotten; rather they raise the quality of delivery in future projects to all standards.



Alun Watkins of Linc Cymru at the UK Passivhaus Conference 2019As Alun Watkins of Linc Cymru explained to the audience at the UK Passivhaus Conference 2019, the housing association considers that through the course of this project they’ve learned key lessons that could enable them to be looking at as little as 5% additional costs for future Passivhaus projects, echoing the findings in the recent Passivhaus construction costs report. Much of it is to do with integrating Passivhaus into the process from the start, with early training for the project team, early engagement of experienced team members (for M&E, project management and Passivhaus design) and early contractor involvement. Improving the procurement process is also key, and the Passivhaus Trust will be addressing this next year, with the initiation of procurement clubs for clients planning Passivhaus projects. Look out for more news on this in 2020.

Of course, lessons learned and invaluable experience gained on a first Passivhaus project also makes the second and subsequent Passivhaus projects much easier! Phase 2 of the development, following the purchase of the adjacent police station site, is now on the horizon. Caerphilly Council is keen for this second phase to also pursue Passivhaus, and with the same design team and the opportunity to negotiate with the same contractor and draw on their experience, the path to Passivhaus is likely to be much smoother.


Caerphilly phase 2 | Linc Cymru

All photos courtesy of Linc Cymru


Further information

Passivhaus at Scale - 2019 UK Passivhaus Conference presentation - Alun Watkins, Linc Cymru

Previous PHT story: Passivhaus delivers well-being in Wales - 16 November 2018

Passivhaus construction costs 

Caerphilly Passivhaus | Childs + Sulzmann 

Construction phase of Caerphilly development is underway | Jehu Group


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1st November 2019

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